Table 2. Assembly of Prunolactone A (1) and Its Unnatural (3′R)-Epimer (16) in a Biomimetic DA Reaction.

Entry	6 (eq)	Base (eq)	Reaction conditions	Yield of 1 (%)	Recovered 6 (yield %)
1	1.5	DABCO (3)	24 h, 25 °C	46	49
2	3.0	DABCO (3)	24 h, 25 °C	57	69
3	1.5	DIPEA (10)	48 h, 25 °C	32	63
4	3.0	DIPEA (10)	24 h, 50 °C	55	72
5	1.5	Et3N (10)	24 h, 50 °C	44	47
6	3.0	Et3N (10)	24 h, 50 °C	59	66
7	1.5	DBU (3)	15 min, 25 °C	15a	73
8	1.5	pyridine (10)	24 h, 25 °C	n/db,c	–
9	1.5	pyridine (10)	24 h, 50 °C	tracesc	–
10	1.5	pyridined	48 h, 50 °C	53	58
11	3.0	pyridined	48 h, 50 °C	57	72

^aThe rest was an intractable mixture.

^bProduct not detected.

^cSM recovered.

^dPyridine used as a solvent.